Ongoing investigations have studied the impact of nonrepinephrine and dopamine upon the energy balance of white Leghorn hens when injected intraventricularly. Body temperature is lowered by the drugs at 9 to 20 C and raised by the drugs at 35 C, even though the drug lower metabolic heat production (MHP) and evaporative heat loss (EHL) at all ambient temperatures. At low air temperatures energy lost by lowering MHP exceeds energy "gain" by lowering EHL, due to the predominance of MHP over EHL. At high air temperatures, EHL predominates over MHP and lowering both results in a net energy gain and a rise in body temperature. Destruction of the norepinephrinergic system by intraventricular injection of either 50, 112, 225, or 300 micro g of 6-hydroxy-dopamine did not affect the thermo-regulatory ability of hens exposed to either 10, 20, or 35C ambient temperatures. Differences appear to exist between mammals and chickens in terms of the role of the hypothalamus in thermoregulation since peripheral, perhaps spinal, inputs are necessary to explain the very small (less than 0.5C) and even reversed changes from the expected change for body temperature when the hypothalamus is locally heated or cooled. Future work will investigate: (1) the impact of serotonin (5-HT) and acetylcholine upon the energy balance of hens, (2) whether either the dopaminergic or a combination of dopaminergic and norepinephrinergic centers are required for thermoregulation, (3) the thermoregulatory responses to local heating and cooling of the spinal cord of chickens at 10, 20, or 35 C and (4) the relative influence of hypothalamic and spinal cord temperatures on thermoregulation by additive and antagonistic local thermal stimulations of both sites.